COM in plain C, Part 6

// Registers our IExample.DLL as a COM component.

#include <windows.h>
#include <tchar.h>
#include <initguid.h>
#include "../IExample/IExample.h"


// These first 3 strings will change if you create your own object
static const TCHAR	OurDllName[] = _T("IExample.dll");
static const TCHAR	ObjectDescription[] = _T("IExample COM component");
static const TCHAR	FileDlgTitle[] = _T("Locate IExample.dll to register it");

static const TCHAR	FileDlgExt[] = _T("DLL files\000*.dll\000\000");
static const TCHAR	ClassKeyName[] = _T("Software\\Classes");
static const TCHAR	CLSID_Str[] = _T("CLSID");
static const TCHAR	InprocServer32Name[] = _T("InprocServer32");
static const TCHAR	ThreadingModel[] = _T("ThreadingModel");
static const TCHAR	BothStr[] = _T("both");
static const TCHAR	GUID_Format[] = _T("{%08lX-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X}");





/************************ stringFromCLSID() ***********************
 * Converts an object's GUID (array) to an ascii string (in a special
 * format where there are groups of ascii digits separated by a dash).
 * NOTE: Using wsprintf() avoids needing to load ole32.dll just to
 * call StringFromCLSID(). We're just doing the same thing it would do.
 */

static void stringFromCLSID(LPTSTR buffer, REFCLSID ri)
{
	wsprintf(buffer, &GUID_Format[0],
		((REFCLSID)ri)->Data1, ((REFCLSID)ri)->Data2, ((REFCLSID)ri)->Data3, ((REFCLSID)ri)->Data4[0],
		((REFCLSID)ri)->Data4[1], ((REFCLSID)ri)->Data4[2], ((REFCLSID)ri)->Data4[3],
		((REFCLSID)ri)->Data4[4], ((REFCLSID)ri)->Data4[5], ((REFCLSID)ri)->Data4[6],
		((REFCLSID)ri)->Data4[7]);
}





/************************ cleanup() ***********************
 * Removes all of the registry entries we create in WinMain.
 * This is called to do cleanup if there's an error
 * installing our DLL as a COM component.
 */

static void cleanup(void)
{
	HKEY		rootKey;
	HKEY		hKey;
	HKEY		hKey2;
	TCHAR		buffer[39];

	stringFromCLSID(&buffer[0], (REFCLSID)(&CLSID_IExample));

	// Open "HKEY_LOCAL_MACHINE\Software\Classes"
	if (!RegOpenKeyEx(HKEY_LOCAL_MACHINE, &ClassKeyName[0], 0, KEY_WRITE, &rootKey))
	{
		// Delete our CLSID key and everything under it
		if (!RegOpenKeyEx(rootKey, &CLSID_Str[0], 0, KEY_ALL_ACCESS, &hKey))
		{
			if (!RegOpenKeyEx(hKey, &buffer[0], 0, KEY_ALL_ACCESS, &hKey2))
			{
				RegDeleteKey(hKey2, &InprocServer32Name[0]);

				RegCloseKey(hKey2);
				RegDeleteKey(hKey, &buffer[0]);
			}

			RegCloseKey(hKey);
		}

		RegCloseKey(rootKey);
	}
}





/************************** WinMain() ************************
 * Program Entry point
 */

int WINAPI WinMain(HINSTANCE hinstExe, HINSTANCE hinstPrev, LPSTR lpszCmdLine, int nCmdShow)
{
	int				result;
	TCHAR			filename[MAX_PATH];

	{
	OPENFILENAME	ofn;

	// Pick out where our DLL is located. We need to know its location in
	// order to register it as a COM component
	lstrcpy(&filename[0], &OurDllName[0]);
	ZeroMemory(&ofn, sizeof(OPENFILENAME));
	ofn.lStructSize = sizeof(OPENFILENAME);
	ofn.lpstrFilter = &FileDlgExt[0];
	ofn.lpstrFile = &filename[0];
	ofn.nMaxFile = MAX_PATH;
	ofn.lpstrTitle = &FileDlgTitle[0];
	ofn.Flags = OFN_FILEMUSTEXIST|OFN_EXPLORER|OFN_PATHMUSTEXIST;
	result = GetOpenFileName(&ofn);
	}

	if (result > 0)
	{
		HKEY		rootKey;
		HKEY		hKey;
		HKEY		hKey2;
		HKEY		hkExtra;
		TCHAR		buffer[39];
		DWORD		disposition;

		// Assume an error
		result = 1;

		// Open "HKEY_LOCAL_MACHINE\Software\Classes"
		if (!RegOpenKeyEx(HKEY_LOCAL_MACHINE, &ClassKeyName[0], 0, KEY_WRITE, &rootKey))
		{
			// Open "HKEY_LOCAL_MACHINE\Software\Classes\CLSID"
			if (!RegOpenKeyEx(rootKey, &CLSID_Str[0], 0, KEY_ALL_ACCESS, &hKey))
			{
				// Create a subkey whose name is the ascii string that represents
				// our IExample2 object's GUID
				stringFromCLSID(&buffer[0], (REFCLSID)(&CLSID_IExample));
				if (!RegCreateKeyEx(hKey, &buffer[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hKey2, &disposition))
				{
					// Set its default value to some "friendly" string that helps
					// a user identify what this COM DLL is for. Setting this value
					// is optional. You don't need to do it
					RegSetValueEx(hKey2, 0, 0, REG_SZ, (const BYTE *)&ObjectDescription[0], sizeof(ObjectDescription));

					// Create an "InprocServer32" key whose default value is the path of this DLL
					if (!RegCreateKeyEx(hKey2, &InprocServer32Name[0], 0, 0, REG_OPTION_NON_VOLATILE, KEY_WRITE, 0, &hkExtra, &disposition))
					{
						if (!RegSetValueEx(hkExtra, 0, 0, REG_SZ, (const BYTE *)&filename[0], lstrlen(&filename[0]) + 1))
						{
							// Create a "ThreadingModel" value set to the string "both" (ie, we don't need to restrict an
							// application to calling this DLL's functions only from a single thread. We don't use global
							// data in our IExample functions, so we're thread-safe)
							if (!RegSetValueEx(hkExtra, &ThreadingModel[0], 0, REG_SZ, (const BYTE *)&BothStr[0], sizeof(BothStr)))
							{
								result = 0;
								MessageBox(0, "Successfully registered IExample.DLL as a COM component.", &ObjectDescription[0], MB_OK);
							}
						}

			// Close all keys we opened/created.

						RegCloseKey(hkExtra);
					}

					RegCloseKey(hKey2);
				}

				RegCloseKey(hKey);
			}

			RegCloseKey(rootKey);
		}

		// If an error, make sure we clean everything up
		if (result)
		{
			cleanup();
			MessageBox(0, "Failed to register IExample.DLL as a COM component.", &ObjectDescription[0], MB_OK|MB_ICONEXCLAMATION);
		}
	}

	return(0);
}